1. Technical Field
Embodiments are directed to a data bus control scheme for an image sensor and an image sensor including the same.
2. Description of Related Art
High speed Data BUS (DBUS) are increasingly important for realizing high speed operation of integrated circuits (ICs). DBUS are used to serialize a digital signal to realize high speed analog to digital conversion (ADC). High speed ADC is needed to realize high resolution and high frame rate CMOS image sensor (CIS).
In a conventional system, a digital signal converted from analog signal is supplied to a memory array. Digital signals from the memory array are loaded on DBUS, which has been precharged to a predetermined voltage. Each cell of the memory array is activated by allocated address and the data from the activated cell is loaded onto DBUS. A sense amplifier senses and amplifies the data loaded in the DBUS. In such a system, one cycle includes three sequential operations, i.e., a DBUS precharge, data loading onto the DBUS from the activated memory cell, and evaluation, i.e., sensing/amplification. Additional circuitry is required to generate these control signals and a clock delay needs to be adjusted with variation in operational frequency.